1. Field of Invention
The field of the present invention relates in general to wireless local area networks (WLAN) including wireless access points (WAP) and methods of channel selection thereon.
2. Description of the Related Art
Home and office networks, a.k.a. wireless local area networks (WLAN) are established using a device called a Wireless Access Point (WAP). The WAP may include a router. The WAP wirelessly couples all the devices of the home network, e.g. wireless stations such as: computers, printers, televisions, digital video (DVD) players, security cameras and smoke detectors to one another and to the Cable or Subscriber Line through which Internet, video, and television is delivered to the home. Most WAPs implement the IEEE 802.11 standard which is a contention based standard for handling communications among multiple competing devices for a shared wireless communication medium on a selected one of a plurality of communication channels. The frequency range of each communication channel is specified in the corresponding one of the IEEE 802.11 protocols being implemented, e.g. “a”, “b”, “g”, “n”, “ac”, “ad”. Communications follow a hub and spoke model with a WAP at the hub and the spokes corresponding to the wireless links to each ‘client’ device.
After selection of a single communication channel for the associated home network, access to the shared communication channel relies on a multiple access methodology identified as Collision Sense Multiple Access (CSMA). CSMA is a distributed random access methodology first introduced for home wired networks such as Ethemet for sharing a single communication medium, by having a contending communication link back off and retry access to the line if a collision is detected, i.e. if the wireless medium is in use.
Communications on the single communication medium are identified as “simplex” meaning, communications from a single source node to one target node at one time, with all remaining nodes capable of “listening” to the subject transmission. Starting with the IEEE 802.11ac standard and specifically ‘Wave 2’ thereof, discrete communications to more than one target node at the same time may take place using what is called Multi-User (MU) multiple-input multiple-output (MIMO) capability of the WAP.
The IEEE 802.11ac standard also opened up new channel bandwidths, up to 160 MHz in a new WiFi frequency range, i.e. 5 GHz. A large portion of the designated channels in the 5 GHz range, were subject to prior use for weather, airport, and military radar of governmental and civilian entities. The IEEE 802.11ac standard codifies the ongoing and exclusionary entitlement of these entities to these portions of the 5 GHz spectrum. This preferential treatment is reflected in the IEEE 802.11ac standard which proscribes that any channel eligible for radar, e.g. Channels 52-64 and 100-144 in the US, can be used for WiFi only if the radar is not active. Thus a WAP must monitor a channel for an inordinately long time, e.g. at least 60 seconds, before initiating a WLAN. This requirement results in service interruptions or delays in setting up or re-establishing a WLAN on a radar eligible channel. Furthermore, even if the channel is found to have no active radar, the WAP must, after establishing a WLAN thereon, devote a portion of its operation to constantly monitoring the channel for the onset of active radar, and immediately shut down WLAN communications upon detection of same. This general set of protocols and workflows surrounding radar surrounding WiFi access to radar eligible channels is identified as Dynamic Frequency Selection (DFS) with the radar eligible channels identified as DFS channels.
What is needed are improved methods for managing access to radar eligible channels.